In data and voice transmission lines typically used in the telephone industry, the cable consists of a plurality of wire pairs, typically segregated into groups of 50, 100, 200, 400, 600, 1200 or 1800 pairs, which are covered by a pressurized and airtight metallic sheath and a plastic outer protective sheath. Wire pairs extending between a central source and a subscriber have substantial capacitance, resulting in a change in impedance with length. The capacitance effect of the cable conductors has a direct relation on the voice band (300 Hz to 3000 Hz) from any given point--the higher the frequency, the greater the loss or attenuation. Thus, it is conventional to connect inductance or load coils in the conductors to maintain a predetermined impedance to balance and improve the voice frequency characteristics of the cable conductors and to assure maximum signal power transfer between the central source and the subscriber. The load coils are typically connected to wire pairs at predetermined intervals so that the known capacitance of the resulting predetermined wire pairs will be balanced by the inductance of the load coil.
Load coil cases are typically used for housing the plurality of load coils associated with each of the 50, 100, 200, 400, 600, 1200 or 1800 wire pairs. After the individual wire pairs are connected to a corresponding load coil, they are typically assembled in a compact configuration in the load coil case and the load coil case is filled with an appropriate encapsulating or potting compound to keep moisture from affecting the load coils, such as by oxidizing the metallic inductor cores, damaging the insulation of the wires in the load coil, or forming conductive paths between wire pairs which would result in degraded compensation and cross linking and cross talk between wire pairs The load coil may then be stored in pedestal cabinets, in underground manholes, and the like.
In many applications, however, when the subscriber wants high frequency service, each and every load coil located between the source and subscriber must be "unloaded" or bypassed from the wire pair servicing the particular subscriber. In order to bypass the load coil, each load coil case must first be located in the dirt, water, and other debris typically found in the outside plant telephone environment. After the outer and metallic sheaths are removed and the specific wire pair servicing the subscriber is located from the potentially hundreds of wire pairs typically found in telecommunications cables, the load coil is unloaded or bypassed by splicing the wire pair around the load coil. The cable must be recovered with the metallic and plastic sheaths, pressurized and tested for leaks It will be appreciated that a subscriber may alternatively require that a disconnected load coil be reloaded or re-connected to the wire pair in a similar manner. In either case, it may typically take two technicians eight hours or more to complete the splicing operation for each load coil in the subscriber's wire pair.